名词性从句的句法功能(讲义)

1. 掌握名词性从句的分类及各自的句法功能。

2. 初步了解主语从句、宾语从句、表语从句和同位语从句。

重点：名词性从句的分类及判定。

难点：同位语从句与定语从句的辨析。

1. 作为三大从句之一，名词性从句是高中英语中需要重点掌握的知识，也是高考考查的重点。在高考试题中对名词性从句的考查非常频繁，而且出现多年连续考查的情况。

2. 在近年的高考试题中，涉及名词性从句的题目突出了对what, that, whatever等引导词的考查，从考查形式来看，试题的设置也越来越灵活，越来越新颖多样：其一，把两种名词性从句融合在一起考查；其二，与状语从句或强调句型结合起来考查；其三，名词性从句与it 作形式主语、形式宾语相结合的考查。

What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas.

很多科学家相信, 由于地球上长期有水存在, 使地球得以把有害气体和酸性物质溶解在海洋里。

本句包含两个名词性从句，一是由what引导的主语从句，在从句中作believe的宾语；二是由that引导的表语从句。此句还可转换为：

Many scientists believe that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas. (宾语从句)

It is believed by scientists that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas. (主语从句)

名词性从句：具有名词作用的从句。

包含：主语从句，宾语从句，表语从句和同位语从句。

Who will attend the meeting has not been decided. （主语从句）

No one knows who will attend the meeting. （宾语从句）

My question is who will attend the meeting. （表语从句）

The question who will attend the meeting remains to be discussed. （同位语从句）

主语从句

（1）What it was to become was uncertain until between 4. 5 and 3. 8 billion years ago when the dust settled into a solid globe.

地球会变成什么（样子），直到45亿至38亿年前这个云团变成一个固体的球状物，才确定下来。

（2）The earth became so violent that it was not clear whether the shape would last or not.

地球变得激烈动荡，不知道这个固体形状是否会继续存在下去。

（3）What is even more important is that as the earth cooled down, water began to appear on its surface.

更重要的是，随着地球的冷却，地球的表面就开始出现了水。

（4）It was not immediately obvious that water was to be fundamental to the development of life.

水对于生命的发展会起关键作用，这一点在当时并不明显。

（5）Why they suddenly disappeared still remains a mystery.

为什么他们突然消失了，至今还是个谜。

（6）So whether life will continue on the earth for millions of years to come will depend on whether this problem can be solved.

所以, 在未来的数百万年中，生命能否在地球上延续取决于这个问题能否得到解决。

主语从句：在主从复合句中，位于谓语动词之前充当句子主语的从句即为主语从句，主语从句一般位于句首，放在谓语动作之前。如：

What surprised me most was so few people attending the meeting.

最使我吃惊的是参加会议的人这么少。

That he was late for the class again made the teacher very angry.

他又迟到了，这使老师很生气。

有时，主语从句作主语，而谓语部分较短，会使句子结构显得头重脚轻，所以常用it作形式主语，而将真正的主语从句放到后面去，如：

That you should learn some new words by heart is important in learning a foreign language.背单词对学习外语来说很重要。

=It is important in learning a foreign language that you should learn some new words by heart.

When we will start for the trip hasn’t been decided.我们什么时候出行尚未决定。

It doesn’t matter ________ you turn right or left at the crossing—both roads lead to the park.

A. whether

B. how

C. if

D. when

答案：A

思路分析：本题考查名词性从句的引导词。句意为“在这个十字路口你向左或右转弯都没有关系，因为两条路都通向公园”。题干中it作形式主语，所以所选的连词在句中引导主语从句。whether引导名词性从句表示“是否”之意,而且题干中出现了关键信息词or。whether...or...表示“是……还是……”。if引导名词性从句也表示“是否”，但引导主语从句、表语从句、同位语从句等只能用whether而不能用if。

宾语从句